The present invention generally relates to catheters, and in particular, to a detachable inflation adaptor for a catheter having a low profile valve which may be opened to permit inflation or deflation of a catheter balloon, such as an occlusion balloon, and which may be closed when it is desirable to maintain the catheter balloon in an inflated state.
Guidewires are conventionally used to guide the insertion of various medical instruments, such as catheters, to a desired treatment location within a patient's vasculature. In a typical procedure, the clinician forms an access point for the guidewire by creating an opening in a peripheral blood vessel, such as the femoral artery. The highly flexible guidewire is then introduced through the opening into the peripheral blood vessel, and is then advanced by the clinician through the patient's blood vessels until the guidewire extends across the vessel segment to be treated. Various treatment catheters, such as a balloon dilatation catheter for a percutaneous transluminal coronary angioplasty, may then be inserted over the guidewire and similarly advanced through vasculature until they reach the treatment site.
In certain treatment procedures, it is desirable to successively introduce and then remove a number of different treatment catheters over a guidewire that has been placed in a particular location. In other words, one treatment catheter is "exchanged" for another over a single guidewire. Such an exchange typically involves withdrawing the treatment catheter over the guidewire until the treatment catheter is fully removed from the patient and the portion of the guidewire which extends from the patient. The guidewire is then available to act as a guide for a different treatment catheter.
In emboli containment devices, which typically utilize two occlusion balloons to form a chamber, it may be desirable to exchange therapeutic catheters without deflating the occlusion balloons. Further, it is sometimes advantageous to anchor the guidewire during the exchange. As can be readily appreciated, the withdrawal of treatment catheters over a placed guidewire may result in the guidewire being displaced from its position. To overcome this difficulty, the prior art has developed "anchorable" guidewires, which generally feature some structure on their distal ends to releasably secure the guidewire at a particular location in the patient for the duration of the medical procedure. One such anchorable guidewire is disclosed in U.S. Pat. No. 5,167,239 to Cohen et al., which discloses a hollow guidewire with an inflation lumen and an expandable balloon on its end. The Cohen guidewire is positioned in the same manner as a conventional wire guidewire, but once placed, its expandable balloon is inflated to contact the surrounding vasculature, thereby preventing the guidewire from being displaced.
Because a permanent inflation manifold, of the type used with conventional catheters having an inflatable balloon, would prevent other catheters from being inserted over the Cohen guidewire, the Cohen device also includes a removable inflation manifold, and a check valve to maintain the balloon in the inflated state when the manifold is removed. The check valve apparatus used by the Cohen device is relatively bulky, and is described as having an outer diameter in its preferred embodiment of 0.0355 inches. Consequently, any treatment catheter intended to be inserted over the Cohen device must have an interior guidewire lumen larger than the outer diameter of the Cohen valve, which for the preferred embodiment, requires an interior lumen with a diameter of more than 0.0355 inches.
As is readily appreciated by those of skill in the art, increasing the interior lumen size of a treatment catheter results in an increase in the outer diameter of the treatment catheter. For treatment procedures which take place in vasculature having a large blood vessel diameter, such as iliac arteries, a treatment catheter guidewire lumen of a size necessary to accommodate devices such as those described by Cohen would have little or no affect on the ability of the catheter to fit within the blood vessel. However, many blood vessels where it is desirable to apply catheter treatment are quite narrow. For example, the left coronary arteries are blood vessels having diameters ranging from 2 to 4 mm, and are susceptible to plaque. It would be desirable to use a catheter exchange treatment procedure, such as angioplasty, to treat such lesions, but the narrow diameter of the coronary vessels makes use of anchorable guidewires having large valve diameters impractical.
Consequently, there exists a need for a very low profile catheter valve which can be used with a hollow guidewire. Furthermore, there exists a need for a detachable inflation adaptor which can be used with such low profile valves to open and close them, and to apply inflation or deflation forces to the catheter balloons.